Copper alloy sheet material having a low young&#39;s modulus and method of producing the same

ABSTRACT

{Problems} To provide a copper alloy material, having a low Young&#39;s modulus that is required of electrical or electronic parts, such as connectors. 
     {Means to solve} A copper alloy sheet material for electrical or electronic parts, having an alloy composition containing any one or both of Ni and Co in an amount of 0.5 to 5.0 mass % in total, and Si in an amount of 0.2 to 1.5 mass %, with the balance being Cu and inevitable impurities, wherein the copper alloy sheet material has a 0.2% proof stress in the rolling direction of 500 MPa or more, an electrical conductivity of 30% IACS or more, a Young&#39;s modulus of 110 GPa or less, and a factor of bending deflection of 105 GPa or less.

TECHNICAL FIELD

The present invention relates to a copper alloy sheet material having high mechanical strength and high electrical conductivity, which is suitable as a material for electrical or electronic parts, such as connectors, and further having a low Young's modulus, and the present invention also relates to a method of producing the same.

BACKGROUND ART

In recent years, wirings of various electrical or electronic equipments have been subjected to further intricacy and higher integration, due to the development of electronics industries. Along this trend, the opportunity for copper alloys to be used for electrical or electronic parts is ever increasing. In particular, electrical or electronic parts, such as connectors, are demanded to narrow the pitch, lower the height, enhance the reliability higher, and lower the costs. Thus, in order to satisfy these demands, copper alloy sheet materials that can be used in electrical or electronic parts, such as connectors, are required to have high mechanical strength and high electrical conductivity and to simultaneously have excellent press formability, so as to be formed into thin sheets and to be pressed into complicated shapes.

In order to use as materials for terminals, it is preferable for the materials to have a tensile strength in the rolling direction (RD) of 500 MPa or more, as a mechanical strength that does not cause deformation upon putting-in and pulling-out (insertion and extraction) of the terminals or against bending thereof, and to have an electrical conductivity of 30% IACS or more, so as to suppress the Joule heat generation caused by electric current conduction.

Furthermore, hitherto, the material for connectors has been required to have a large Young's modulus so that the resultant connectors become small-sized, and a large stress may be obtained with a small displacement. However, more strict dimensional accuracy is demanded for terminals themselves, and more strict criteria are applied to, such as the operation control in pressing or molding technology, or the control criteria, for example, of the sheet thickness of the material for connectors or fluctuations in the residual stress, which resulted in an increase in the costs conversely. Under the situations, recently, there has been a demand for a design that allows dimensional fluctuations, by adopting a structure which undergoes large spring displacement, by using a material for connectors small in Young's modulus. Thus, there has been a demand for the material having a Young's modulus in the rolling direction of 110 GPa or less, preferably 100 GPa or less.

So far, brass, phosphor bronze, and the like have been generally used as the materials for connectors. Both brass and phosphor bronze have a Young's modulus in the rolling direction of about 110 to 120 GPa, which is smaller as compared with the Young's modulus of 128 GPa of pure copper, and brass and phosphor bronze are widely used as low Young's modulus materials. However, these copper alloys each have an electrical conductivity as low as 30% IACS or less, and may not be used for connectors in the applications where large electric current is to pass. Thus, attention has been paid to Corson-based alloy, which has a moderate degree of electrical conductivity, and the amount of use of the alloy is increasing. However, this Corson-based alloy has a Young's modulus of about 130 GPa, and due to this, there is a demand for lowering of the Young's modulus of connector materials. Furthermore, depending on a designer of connectors, there are cases where connectors are designed based not on the Young's modulus but on the factor of bending deflection (the modulus of longitudinal elasticity upon a bending test), and lowering of the factor of bending deflection is demanded. Generally, Young's modulus represents the modulus of longitudinal elasticity under tensile stress, and the factor of bending deflection represents the modulus of longitudinal elasticity under the complex stress of compressive stress and tensile stress upon bending. Although the values of the Young's modulus and the factor of bending deflection are different from each other, if the Young's modulus is low, the factor of bending deflection tends to be a low value.

A lowering of the Young's modulus and a lowering of the factor of bending deflection are achieved not only by adding zinc (Zn) or phosphor (P) to copper, but also by controlling the crystal orientation. For example, as described in Patent Literature 1 and Patent Literature 2, when pure copper is recrystallized by a heat treatment after rolling at a high working ratio, cube orientation (1 0 0) <1 0 0> increases in the direction (ND) normal to the rolling direction of the sheet material, and thereby the Young's modulus lowers, while flexibility becomes favorable. However, in a Corson-based alloy, if simply the cold-rolling ratio before recrystallization is increased, the cube orientation is not increased, and it is difficult to control the Young's modulus.

CITATION LIST Patent Literatures

-   Patent Literature 1: JP-A-55-54554 (“JP-A” means unexamined     published Japanese patent application) -   Patent Literature 2: Japanese Patent No. 3009383

SUMMARY OF INVENTION Technical Problem

The present invention is contemplated for providing a copper alloy sheet material for electrical or electronic parts, such as connectors, which can simultaneously satisfy high mechanical strength, high electrical conductivity, and low Young's modulus that are required of materials for electrical or electronic parts, such as connectors, along with the development of electronics industries, and for providing a method of producing the same.

Solution to Problem

According to the present invention, there is provided the following means:

(1) A copper alloy sheet material for electrical or electronic parts, having an alloy composition containing any one or both of Ni and Co in an amount of 0.5 to 5.0 mass % in total, and Si in an amount of 0.2 to 1.5 mass %, with the balance being Cu and inevitable impurities,

wherein the copper alloy sheet material has a 0.2% proof stress in the rolling direction of 500 MPa or more, an electrical conductivity of 30% IACS or more, a Young's modulus of 110 GPa or less, and a factor of bending deflection of 105 GPa or less.

(2) The copper alloy sheet material for electrical or electronic parts described in item (1), wherein the copper alloy sheet material has an area ratio of (1 0 0) plane oriented toward the rolling direction, which is obtained by analyzing the copper alloy sheet material with EBSD, is 30% or more. (3) The copper alloy sheet material for electrical or electronic parts described in item (1) or (2), wherein the copper alloy sheet material has an area ratio of (1 1 1) plane oriented toward the rolling direction, which is obtained by analyzing the copper alloy sheet material with EBSD, is 15% or less. (4) The copper alloy sheet material for electrical or electronic parts described in any one of items (1) to (3), wherein the alloy composition further contains Cr in an amount of 0.05 to 0.5 mass %. (5) The copper alloy sheet material for electrical or electronic parts described in any one of items (1) to (4), wherein the alloy composition further contains one, two, or more selected from the group consisting of Zn, Sn, Mg, Ag, Mn, and Zr in an amount of 0.01 to 1.0 mass % in total. (6) The copper alloy sheet material for electrical or electronic parts described in any one of items (1) to (5), which is a material for connectors. (7) A connector, which is composed of the copper alloy sheet material for electrical or electronic parts described in any one of items (1) to (6). (8) A method of producing the copper alloy sheet material for electrical or electronic parts described in any one of items (1) to (7), containing, in this order, the steps of: subjecting a copper alloy to give the alloy composition to casting; hot-rolling; cold-rolling 1; intermediate annealing; cold-rolling 2; solution heat treatment; aging heat treatment; finish cold-rolling; and low-temperature annealing,

wherein the method of producing further contains, conducting at least any one or both of the following steps [1] and [2]:

[1] slowly cooling to 350° C. after the hot-rolling; and

[2] carrying out the intermediate annealing and the cold-rolling 2, repeatedly two times or more.

Advantageous Effects of Invention

The copper-based alloy material according to the present invention and the copper alloy material obtained according to the production method of the present invention each have a low Young's modulus, without impairing the high mechanical strength or/and the high electrical conductivity required of materials for electrical or electronic parts, such as connectors, as compared with conventional Corson-based alloys, and are favorable as a copper alloy material for electrical or electronic parts, such as connectors.

MODE FOR CARRYING OUT THE INVENTION

Preferable embodiments of the copper alloy sheet material of the present invention will be described in detail. Herein, the term “copper alloy material” means a product obtained after a copper alloy base material is worked into a predetermined shape (for example, sheet, strip, foil, rod, or wire). Among them, a sheet material refers to a material which has a specific thickness, is stable in the shape, and is extended in the plane direction, and in a broad sense, the sheet material is meant to encompass a strip material. Herein, with regard to the sheet material, the term “surface layer of the material (or material surface layer)” means the “sheet surface layer,” and the term “position of a depth of the material” means the “position in the sheet thickness direction.” There are no particular limitations on the thickness of the sheet material, but when it is considered that the thickness should well exhibit the effects of the present invention and should be suitable for practical applications, the thickness is preferably 8 to 800 μm, and more preferably 50 to 70 μm.

In the copper alloy sheet material of the present invention, the characteristics are defined by the accumulation ratio of the atomic plane in a predetermined direction of a rolled sheet, but this will be considered enough if the copper alloy sheet material has such characteristics in the present invention. The shape of the copper alloy sheet material is not intended to be limited to a sheet material or a strip material, and it is noted that in the present invention, a tube material can also be construed and treated as a sheet material.

With respect to the copper alloy material of the present invention (as a representative shape, a sheet material), which is a precipitate-type copper alloy material, such as Corson-based, having a low Young's modulus and a low factor of bending deflection, first, the alloy composition thereof, followed by the texture thereof, will be described.

(Component Composition of the Copper Alloy Material)

The reasons for limiting the chemical component composition in the copper alloy material of the present invention, which are the premises for attaining high mechanical strength, will be described (the unit for the content “%” described herein is all in terms of “mass %”).

(Ni: 0.5 to 5.0%)

Ni is an element that is contained together with Si, which will be described below, to form a Ni₂Si phase that is precipitated by an aging treatment, to contribute to enhancement of the mechanical strength of the resultant copper alloy material. If the content of Ni is too small, the Ni₂Si phase is insufficient, and the tensile strength of the copper alloy material may not be enhanced. On the other hand, if the content of Ni is too large, the electrical conductivity lowers, and the hot-rolling workability is deteriorated. Thus, the content of Ni is set to the range of 0.5 to 5.0%, preferably 1.5 to 4.0%.

(Co: 0.5 to 5.0%)

Co is an element that is contained together with Si, to form a Co₂Si phase that is precipitated by the aging treatment, to contribute to enhancement of the mechanical strength of the resultant copper alloy material. When it is intended to enhance electrical conductivity, it is preferable to contain Co alone, without containing Ni. If the content of Co is too small, the Co₂Si phase is insufficient, and the tensile strength of the copper alloy material may not be enhanced. On the other hand, if the content of Co is too large, the electrical conductivity lowers, and the hot-rolling workability is deteriorated. Thus, the content of Co is set to the range of 0.5 to 5.0%, preferably 0.8 to 3.0%, more preferably 1.1 to 1.7%.

The copper alloy material may contain both of these Ni and Co, but their content is set to 0.5 to 5.0% in total. When containing both of Ni and Co, both Ni₂Si and Co₂Si are precipitated upon the aging treatment, to enhance the aging strength. If the total content of Ni and Co is too small, the tensile strength may not be enhanced, and if the total content is too large, electrical conductivity and hot-rolling workability are deteriorated. Thus, the total content of Ni and Co is set in the range of 0.5 to 5.0%, preferably 0.8 to 4.0%.

(Si)

Si is contained together with the Ni and/or Co, to form the Ni₂Si phase and/or Co₂Si phase that are precipitated by the aging treatment, to contribute to enhancement of the mechanical strength of the copper alloy material. The content of Si is set to 0.2 to 1.5%, preferably 0.2 to 1.0%. When the content of Si is set such that the ratio Ni/Si as a stoichiometric ratio is set to 4.2, and the ratio Co/Si as a stoichiometric ratio is set to 4.2, the balance between electrical conductivity and mechanical strength is most favorably achieved. Thus, it is preferable to set the content of Si such that the ratios Ni/Si, Co/Si, and (Ni+Co)/Si are in the range of 3.2 to 5.2, more preferably 3.5 to 4.8.

If Si is excessively contained in an amount outside this range, the tensile strength of the copper alloy material can be enhanced, but the excess amount of Si is made into a solid solution in the matrix of copper, to lower the electrical conductivity of the copper alloy material. Further, if Si is contained in excess, the casting property in casting, and/or hot- and cold-rolling workability are also deteriorated, to result in being apt to occurring casting cracks or rolling cracks. On the other hand, if the content of Si is outside this range and too small, the precipitated phase of Ni₂Si and/or Co₂Si is insufficiently formed, and the tensile strength of the material may not be enhanced.

(Cr)

In addition to the compositions described above, the copper alloy may also contain Cr in an amount of 0.05 to 0.5 mass %. Cr has an effect of making grains in the alloy finer, to contribute to enhancement of the mechanical strength and/or bending property of the copper alloy material. If the content is too small, the effect is less, and if the content is too large, crystallized products are formed upon casting, to lower the aging strength.

(Other Alloying Elements)

The copper alloy material of the present invention may optionally contain, as an additive element(s) in addition to the above-mentioned basic composition, one, two or more of Sn: 0.01 to 1.0%, Zn: 0.01 to 1.0%, Ag: 0.01 to 1.0%, Mn: 0.01 to 1.0%, Zr: 0.1 to 1.0%, and Mg: 0.01 to 1.0%, each in terms of mass %, in a total amount of 0.01 to 1.0%. These elements are elements, which have a common action/effect of further enhancing any of high mechanical strength or electrical conductivity, or low Young's modulus, each of which is a target to be exhibited by the copper alloy material of the present invention, and which, in addition to this or instead of this, further enhance other properties (stress relaxation resistance, and the like). The characteristic actions/effects and the significance of the content ranges of the respective elements will be described below.

(Sn)

Sn is an element that mainly enhances the mechanical strength of the resultant copper alloy material, and in the case where the material is utilized in applications where these characteristics are regarded as important, Sn is selectively contained. If the content of Sn is too small, the strength-enhancing effect is less. On the other hand, when Sn is contained, the electrical conductivity of the copper alloy material is generally lowered. In particular, if the content of Sn is too large, it is difficult to attain the electrical conductivity of the copper alloy material to be 30% IACS or higher. Thus, when contained, the content of Sn is generally set to the range of 0.01 to 1.0%.

(Zn)

By containing Zn, it becomes possible to enhance the migration resistance or heat resistant peelability upon soldering. If the content of Zn is too small, the effect is less. On the other hand, when Zn is contained, the electrical conductivity of the copper alloy material is generally lowered, and, if the content of Zn is too large, it is difficult to attain the electrical conductivity of the copper alloy material to be 30% IACS or higher. Thus, the content of Zn is generally set to the range of 0.01 to 1.0%.

(Ag)

Ag contributes to enhancement of the mechanical strength of the copper alloy material. If the content of Ag is too small, the effect is less. On the other hand, even if Ag is contained in excess, the strength-enhancing effect is saturated. Thus, when contained, the content of Ag is generally set to the range of 0.01 to 1.0%.

(Mn)

Mn mainly enhances workability in hot-rolling of the alloy. If the content of Mn is too small, the effect is less. On the other hand, if the content of Mn is too large, the melt fluidity in casting of the copper alloy is deteriorated, thereby to lower the casting yield. Thus, when Mn is contained, the content of Mn is generally set to the range of 0.01 to 1.0%.

(Zr)

Zr mainly makes grains finer, to enhance the mechanical strength and/or bending property of the copper alloy material. If the content of Zr is too small, the effect is less. On the other hand, if the content of Zr is too large, compounds are formed, and the workability in rolling or the like of the copper alloy material is deteriorated. Thus, when Zr is contained, the content of Zr is generally set to the range of 0.01 to 1.0%.

(Mg)

Mg enhances the stress relaxation resistance. Thus, in the case where stress relaxation resistance is required, Mg is selectively contained in an amount in the range of 0.01 to 1.0%. If the content of Mg is too small, the target effect by addition thereof is less, and if the content is too large, the electrical conductivity is lowered. Thus, when contained, the content of Mg is generally set to the range of 0.01 to 1.0%.

Mg, Sn, and Zn each improve the stress relaxation resistance, when added to Cu—Ni—Si-based, Cu—Ni—Co—Si-based, and Cu—Co—Si-based copper alloys. When these elements are added together, as compared with the case where any one of them is added solely, the stress relaxation resistance is further improved by synergistic effects. Further, an effect of remarkably improving solder brittleness is obtained.

The electrical conductivity that is realized by the copper alloy sheet material of the present invention is 30% IACS or more, preferably in the range of 35% IACS or more, and more preferably in the range of 45% IACS or more. There are no particular limitations on the upper limit, but the upper limit is practically 60% IACS or less.

Furthermore, a preferred range of the 0.2% proof stress in the rolling direction that is realized by the copper alloy material of the present invention is 500 MPa or more, more preferably 650 MPa or more, and further preferably in the range of 800 MPa or more. There are no particular limitations on the upper limit, but the upper limit is practically 1,100 MPa or less.

The factor of bending deflection is preferably 105 GPa or less, and more preferably 100 GPa or less. There are no particular limitations on the lower limit, but the lower limit is practically 60 GPa or more.

The Young's modulus is 110 GPa or less, and more preferably 100 GPa or less. There are no particular limitations on the lower limit, but the lower limit is practically 70 GPa or more.

(Crystal Structure)

With respect to the crystal structure of the copper alloy material of the present invention, in particular, in order to realize a low Young's modulus and a low factor of bending deflection, it is preferable to have a crystal structure in which the area ratio of (1 0 0) plane oriented toward the rolling direction (RD) is 30% or more, in the results of analysis from the RD according to the SEM-EBSD method. Herein, all grains having an orientation in which the angle formed by the rolling direction (RD) of the sheet material and the normal direction of the relevant plane is 10° or less, are defined to have the (1 0 0) plane that is oriented toward the RD.

In the case of a copper alloy sheet material, the material mainly forms crystal textures called cube orientation, Goss orientation, brass orientation, copper orientation, S orientation, and the like, which will be described below, and has crystal faces corresponding to those orientations, respectively.

The formation of these crystal textures occurs differently, even in the case of the same crystal system, depending on the differences in the methods of working and heat treatment. The method of indicating the crystal orientation in the present specification is such that a Cartesian coordinate system is employed, representing the rolling direction (RD) of the material in the X-axis, the transverse direction (TD) in the Y-axis, and the direction (ND) normal to the rolling direction in the Z-axis, various regions in the material are indicated in the form of (h k l) [u v w], using the index (h k l) of the crystal plane that is perpendicular to the Z-axis (i.e. parallel to the rolling direction) and the index [u v w] in the crystal direction parallel to the X-axis (i.e. perpendicular to the rolling direction). Further, the orientation that is equivalent based on the symmetry of the cubic crystal of a copper alloy is indicated as {h k l}<u v w>, using parenthesis symbols representing families, such as in (1 3 2) [6 −4 3], and (2 3 1) [3 −4 6]. In accordance with the expressions as described above, the respective orientations are expressed as follows.

As representative crystal orientations that are exhibited by a FCC metal, components expressed by the following indices are general.

Cube orientation {0 0 1} <1 0 0> Rotated-cube orientation {0 1 2} <1 0 0> Goss orientation {0 1 1} <1 0 0> Rotated-Goss orientation {0 1 1} <0 1 1> Brass orientation {0 1 1} <2 1 1> Copper orientation {1 1 2} <1 1 1> S orientation {1 2 3} <6 3 4> P orientation {0 1 1} <1 1 1>

In the crystal structures of a conventional copper alloy material sheet, when the constituent proportions of these crystal faces change, the elastic behavior of the sheet material changes.

It is known that copper alloys exhibit orientations such as described above, however, as we have keenly studied, we found that it is effective to increase the area ratio of the (1 0 0) plane that is oriented toward the RD in decreasing the Young's modulus and the factor of bending deflection. Examples of the orientation component in which the (1 0 0) plane is oriented toward the RD include the aforementioned cube orientation, Rotated-cube orientation, Goss orientation, and the like. With respect to the crystal texture of a conventional Corson-based high strength copper alloy sheet, the inventors of the present invention confirmed that when the copper alloy sheet is produced according to a conventional method, the S orientation {1 2 3}<6 3 4> or/and the brass orientation {0 1 1}<2 1 1>, other than the cube orientation {0 0 1}<1 0 0>, constitutes the main component, and the proportion of the cube orientation is lowered, while the Young's modulus and the factor of bending deflection become high. In particular, we confirmed that in the case where there are many (1 1 1) planes in the RD direction, the Young's modulus and the factor of bending deflection become higher.

Thus, for the crystal texture of the copper alloy sheet of the present invention, it is preferable that, among the crystal faces oriented toward the RD, the area ratio of crystal faces in which the angle formed by the two vectors of the plane orientation {for example, the normal direction of the (1 0 0) plane} and the RD, is 10° or less, be 30% or more, thereby to allow a crystal texture having a low Young's modulus and a low factor of bending deflection. The area ratio of the (1 0 0) plane oriented toward the RD is more preferably 40% or more, and even more preferably 50% or more. When the area ratio of the (1 0 0) plane that is oriented toward the RD is increased as such, the Young's modulus can be set to 110 GPa or less, and the factor of bending deflection can be set to 105 GPa or less. This is because the area ratio of the crystal face of (1 0 0) oriented toward the RD, which is low in the Young's modulus and factor of bending deflection, increases. Furthermore, as the area ratio of the crystal face of (1 1 1) oriented toward the RD, which is high in the Young's modulus and factor of bending deflection, decreases, the Young's modulus can be lowered. The area ratio of the (1 1 1) plane oriented toward the RD is preferably 15% or less, and more preferably 10% or less.

In the crystal texture of the copper alloy sheet, the measurement of the area ratio of the (1 0 0) plane oriented toward the RD is carried out by analyzing the electron-microscopic texture by SEM with EBSD. Herein, a range containing 400 or more grains (on, for example, in a sample area which measures 800 μm on each of the four sides) is scanned in a stepwise manner at an interval of 1 μm, to analyze the orientation. Since the distribution of these orientations varies along the sheet thickness direction, it is preferable to determine the area ratio by taking some arbitrary points in the sheet thickness direction, to determine the orientation distribution by taking an average of the data thus obtained.

This SEM-EBSD method is an abbreviation of the Scanning Electron Microscopy-Electron Back Scattered Diffraction Pattern method. That is, the method involves, irradiating individual grains described in a scanning electron microscope (SEM) image with an electron beam, and identifying the individual crystal orientations from the diffracted electrons.

The method of indicating the crystal orientation in the present specification is such that a Cartesian coordinate system is employed, representing the rolling direction (RD) of the material in the X-axis, the transverse direction (TD) in the Y-axis, and the direction (ND) normal to the rolling direction in the Z-axis, and the proportion of regions in which the (1 0 0) plane is oriented toward the RD is defined as the area ratio thereof. The angle formed by the two vectors of the normal direction of the (1 0 0) plane of each grain within the measured region and the RD is calculated, and the sum of the area is calculated for the regions having atomic planes in which this angle is 10° or less. A value obtained by dividing this sum by the total measured area is defined as the area ratio (%) of regions having atomic planes in which the angle formed by the normal direction of the (1 0 0) plane and the RD is 10° or less.

That is, in the present invention, in connection with the accumulation of those atomic planes oriented toward the rolling direction (RD) of the rolled sheet, the region having atomic planes in which the angle formed by the normal direction of the (1 0 0) plane and the RD is 10° or less, represents a region having planes oriented toward the rolling direction (RD) of the rolled sheet, that is, in connection with the accumulation of atomic planes facing to the RD, a region combining the (1 0 0) plane itself which adopts the rolling direction (RD) of the rolled sheet as the normal direction, which is an ideal orientation, with the atomic planes in which the angle formed by the normal direction of the (1 0 0) plane and the RD is 10° or less (i.e. the sum of areas of these planes). Hereinafter, these planes are collectively referred to as the (1 0 0) plane oriented toward the RD, and these regions are simply referred to as a region of atomic planes in which the (1 0 0) plane is oriented toward the RD. Furthermore, the same also applies to the (1 1 1) plane oriented toward the RD.

When conducting the EBSD analysis, in order to obtain a clear Kikuchi-line diffraction image, it is preferable that the analysis is conducted, after mirror polishing of the substrate surface, with polishing particles of colloidal silica, after mechanical polishing. Further, unless otherwise specified, the measurement is carried out from the ND direction of the sheet surface.

Herein, the features of the EBSD analysis will be explained in comparison with the X-ray diffraction analysis. First, the first feature is that there are crystal orientations that cannot be measured by the X-ray diffraction analysis, and they are the S-orientation and the BR orientation. In other words, by employing EBSD, for the first time, information on the S-orientation and the BR-orientation are obtained, and the relationship between the metal texture to be specified by the orientations and the actions/effects thereof is elucidated. The second feature is that X-ray diffraction analyzes the quantity of the crystal orientation that is included in the range of about ±0.5° with respect to ND//{h k l}, while EBSD analyzes the quantity of the crystal orientation that is included in the range of ±10° with respect to the relevant orientation. Therefore, when an EBSD analysis is conducted, a huge range of comprehensive information on the metal texture is obtained, and those states that cannot be easily specified by X-ray diffraction in the overall alloy material can be clarified. As explained above, the information obtainable by an EBSD analysis and the information obtainable by an X-ray diffraction analysis are different from each other in the contents and the natures. Unless otherwise specified, in the present specification, the results of EBSD are results obtained in connection with the ND direction of a copper alloy sheet material.

(Production Conditions)

Next, some preferable production conditions for the copper alloy material of the present invention will be described below. The copper alloy material of the present invention is produced, for example, through the steps of: casting, hot-rolling, slow-cooling, cold-rolling 1, intermediate annealing, cold-rolling 2, solution heat treatment, aging heat treatment, finish cold-rolling, and low-temperature annealing. The copper alloy material of the present invention can be produced, with facilities almost similar to those conventional ones for Corson-based alloy. In order to obtain predetermined properties as well as a predetermined crystal texture, it is necessary to appropriately control the production conditions in the steps. In this regard, the copper alloy material of the present invention can be produced, by carrying out, under the given conditions, at least any of treatments and/or workings selected from, the treatments and/or workings after the hot-rolling, and the cold-rolling and intermediate annealing before the solution treatment.

The casting is carried out to a molten copper alloy having its components set to any of the composition ranges described above, to cast into an ingot. Then, the resultant ingot is face-milled, followed by subjecting to heating or a homogenization heat treatment at 800 to 1,000° C., and then hot-rolling. Herein, in the conventional methods of producing Corson-based alloys, the alloy is quenched immediately after the hot-rolling, by water-quenching or the like. On the other hand, a preferable first embodiment of the method of producing the copper alloy material of the present invention is characterized in that the copper alloy material is not subjected to quenching but is subjected to slow-cooling, to increase the (1 0 0) plane oriented toward the RD after the hot-rolling. The cooling speed in the slow-cooling is preferably 5 K/second or less. The orientation in which the (1 0 0) plane is oriented toward the RD causes a restoration phenomenon at a lower temperature, as compared with other orientations, and thus the area ratio of the orientation in which the (1 0 0) plane is oriented toward the RD, in the hot-rolled texture, can be increased. When the proportion of grains having the orientation in which the (1 0 0) plane is oriented toward the RD, in this hot-rolled texture is increased, the area ratio of the orientation in which the (1 0 0) plane is oriented toward the RD can be increased, in the solution step which is a following step. Since no change occurs in the texture when the temperature at the cooling is lower than 350° C., once the temperature has been cooled-down to below 350° C., the material may be quenched by water-quenching or the like, to shorten the production time period.

Next, after the completion of the hot-rolling and cooling, the resultant surface is face milled, followed by the cold-rolling 1. If the rolling ratio of this cold-rolling 1 is too low, even if the material is thereafter subjected to the production to final products, the brass orientation, the S orientation, or the like develops, and it becomes difficult to increase the area ratio of the (1 0 0) plane. For that reason, the rolling ratio of the cold-rolling 1 is preferably 70% or higher.

After the cold-rolling 1, the intermediate annealing is carried out at 300 to 800° C. for 5 seconds to 2 hours. After the intermediate annealing, the cold-rolling 2 is carried out at a rolling ratio of 3 to 60%. When these intermediate annealing and cold-rolling 2 are repeatedly carried out, the area ratio of the (1 0 0) plane oriented toward the RD can be further increased. Thus, according to a preferable second embodiment of the method of producing the copper alloy material of the present invention, the steps of the intermediate annealing and cold-rolling 2 are repeatedly carried out two times or more.

The solution treatment is carried out under the conditions at 600 to 1,000° C. for 5 seconds to 300 seconds. Since the necessary temperature conditions vary depending on the concentration of Ni and/or Co, it is necessary to select appropriate temperature conditions according to the Ni and/or Co concentrations. If the solution temperature is too low, the mechanical strength is insufficient upon the aging treatment. If the solution temperature is too high, the material is softened more than necessary, and it becomes difficult to control the shape, which is not preferable.

The aging treatment is carried out in the range of at 400 to 600° C. for 0.5 hours to 8 hours. Since the necessary temperature conditions vary depending on the concentration of Ni and/or Co, it is necessary to select appropriate temperature conditions according to the Ni and/or Co concentrations. If the temperature of the aging treatment is too low, the amount of aged precipitate is decreased, to result in the insufficient mechanical strength. Furthermore, if the temperature of the aging treatment is too high, the precipitate is coarsened, to result in lowering of the mechanical strength.

It is preferable to set the working ratio of the finish cold-rolling after the solution treatment, to 50% or less. When the working ratio is appropriately controlled as such, the grains having the (1 0 0) orientation, such as the cube orientation, are suppressed from undergoing orientation rotation to the brass orientation, the copper orientation, or the like. Thus, the resultant copper alloy material is excellent in the physical properties, and a preferred state of the crystal texture can be achieved.

The low-temperature annealing is carried out under the conditions at 300 to 700° C. for 10 seconds to 2 hours. Through this annealing, the stress relaxation resistance and the spring deflection limit, which are required of connector materials, can be enhanced.

In a more preferred production method of obtaining the copper alloy material of the present invention, the steps of both the first embodiment and the second embodiment are carried out, that is, after the hot-rolling, until the temperature reaches at least a temperature range of lower than 350° C., not quenching but slow-cooling (preferably, at a cooling speed of 5 K/sec or less) is carried out, and the steps of the intermediate annealing and cold-rolling 2 are carried out repeatedly two times or more.

TABLE A Step (1) Step (2) Slow- Final Aging Homogeni- cooling solution precipitation zation Hot- after hot- Face- Cold- Intermediate Cold- heat heat Cold- Temper treatment rolling rolling milling rolling 1 annealing rolling 2 treatment treatment rolling annealing Temperature 800 to ∘ ∘ ∘ — 300 to — 600 to 400 to — 300 to ° C. 1,000 800 1,000 600 700 Working ratio — — — — ≧70 — 3 to — — ≦50 — % 60 Time period * — — — — — 5 s to — 5 s to 0.5 h to — 10 s to 2 h 30 s 8 h 2 h * s: sec., m: min., and h: hour

In order to ensure that the copper alloy material of the present invention produced by the method described above has predetermined characteristics, it is enough to verify through an EBSD analysis, whether the properties as well as the crystal texture of the copper alloy material are within the predetermined ranges.

EXAMPLES

The present invention will be described in more detail based on examples given below, but the invention is not meant to be limited by these.

Copper alloy sheets were produced, by casting copper alloys having the respective compositions shown in the following Tables 1 and 2, to evaluate various characteristics, such as mechanical strength (0.2% proof stress), electrical conductivity, Young's modulus, and the like.

First, casting was conducted by a DC (direct chill) method, to obtain ingots with thickness 30 mm, width 100 mm, and length 150 mm. Then, these ingots were heated to 950° C., followed by maintaining at this temperature for one hour, hot-rolling to thickness 14 mm, and slow-cooling at a cooling speed of 1 K/s, and when the temperature dropped to 300° C. or lower, the thus-rolled materials were cooled in water. Then, the respective surface of each of the thus-rolled sheets were face-milled respectively by 2 mm to remove oxide layer, followed by subjecting to cold-rolling 1 at a rolling ratio of 90 to 95%. Then, an intermediate annealing at 350 to 700° C. for 30 minutes was carried out, followed by cold-rolling 2 at a cold-rolling ratio of 10 to 30%. Then, solution treatment was carried out under any of conditions of 700 to 950° C. for 5 seconds to 10 minutes, immediately followed by cooling at a cooling speed of 15° C./sec or higher. Then, an aging treatment at 400 to 600° C. for 2 hours was conducted, under an inert gas atmosphere, followed by finish rolling at a rolling ratio of 50% or less. Thus, the final sheet thickness was set to 0.15 mm. After the finish rolling, the materials were subjected to low-temperature annealing at 400° C. for 30 seconds, thereby to obtain copper alloy sheet materials with various alloying compositions.

With respect to the thus-produced copper alloy sheets, in each test examples, samples cut out from the copper alloy sheets that have been subjected to the low-temperature annealing were utilized, to conduct the tests and evaluations described below.

(1) Area Ratios of Grains of Crystal Orientations

The area ratio of the (1 0 0) plane oriented toward the RD was determined, with respect to the texture of each of the copper alloy sheet samples.

That is, grains having a crystal orientation in which the angle formed by the normal direction of the (1 0 0) plane and the RD was 10° or less, when analyzed by EBSD from the RD direction, were designated as grains having the (1 0 0) plane oriented toward the RD. The area ratio of the (1 0 0) plane oriented toward the RD was specifically determined as follows. Measurement was carried out by an EBSD method in a sample measured region which measured about 800 μm on each of the four sides, under the conditions of a scan step of 1 μm. The measured area was adjusted by taking an area containing 400 or more grains as a reference. As described above, with respect to the (1 0 0) plane of grains having a normal direction of the (1 0 0) plane which formed an angle of 10° or less with the rolling direction (RD) of the sheet material sample, the sum of the areas was determined, and the sum of the areas was divided by the total measured area, to obtain the area ratio (%) of the (1 0 0) plane oriented toward the RD. Herein, those grains in which the angle formed as described above was 10° or less are defined as grains having the same orientation.

Furthermore, the area ratio (%) of the (1 1 1) plane oriented toward the RD was also determined in the same manner.

(2) 0.2% Proof Stress

The 0.2% proof stress was determined, with a No. 5 test piece as stipulated in JIS Z 2201 cut out from the respective sample, according to JIS Z 2241. The 0.2% proof stress is shown by an integer round up by multiple of 5 MPa.

(3) Electrical Conductivity

The electrical conductivity was determined according to JIS H 0505.

(4) Young's Modulus

With respect to Young's modulus, the Young's modulus in a mechanical strength region of the 0.2 proof stress or less was measured, with a tensile tester, by using a strip-like test piece with width 20 to 30 mm, with a strain gauge. The test pieces were cut out in parallel to the rolling direction.

(5) Factor of Bending Deflection

The factor of bending deflection was measured, according to the Japan Copper and Brass Association (JCBA) Technical Standard. The width of the test piece was set to 10 mm, and the length was set to 15 mm. A bending test of a cantilever beam was carried out, and the factor of bending deflection was measured, from the load and the deflection displacement.

These results are shown in Tables 1 and 2.

TABLE 1 Area ratio Area ratio (%) of (100) (%) of (111) Other plane toward plane toward No. Ni Co Si Cr elements RD RD Ex 1 1.5 0.36 Mg: 0.1 51 10 Ex 2 2.3 0.55 55 7 Ex 3 2.3 0.55 0.3 57 10 Ex 4 2.3 0.55 0.1 50 12 Ex 5 2.3 0.55 0.1 Mg: 0.1, 52 9 Sn: 0.1, Zn: 0.5 Ex 6 2.3 0.55 Ag: 0.1 57 11 Ex 7 2.3 0.55 Mn: 0.1 50 14 Ex 8 2.3 0.55 Zr: 0.1 52 9 Ex 9 3.8 0.90 0.1 53 5 Ex 10 3.8 0.90 0.1 Mg: 0.1, 55 6 Sn: 0.1, Zn: 0.5 Ex 11 3.8 0.90 Sn: 0.1 56 11 Ex 12 3.8 0.90 0.2 45 13 Ex 13 4.9 1.17 Mg: 0.1 58 5 Ex 14 4.9 1.17 56 7 Ex 15 4.9 1.17 Mg: 0.1, 54 13 Sn: 0.1, Zn: 0.5 Ex 16 1.2 1.2 0.57 Mg: 0.1 52 9 Ex 17 1.3 0.8 0.50 Mg: 0.1, 54 8 Sn: 0.1, Zn: 0.5 Ex 18 1.3 0.8 0.50 51 6 Ex 19 2.1 0.7 0.67 0.1 50 10 Ex 20 2.4 1.2 0.86 51 8 Ex 21 0.8 2.6 0.81 52 4 Ex 22 0.6 2.8 0.81 51 10 Ex 23 0.8 0.19 Mg: 0.1 54 13 Ex 24 1.4 0.33 Mg: 0.1 50 10 Ex 25 2.3 0.55 48 8 Ex 26 3.1 0.74 Mg: 0.1, 42 14 Sn: 0.1, Zn: 0.5 Ex 27 3.6 0.86 Ag: 0.1 50 10 Ex 28 1.2 1.2 0.75 Mg: 0.1 52 10 Ex 29 1.2 1.2 0.46 Mg: 0.1 52 10 Factor of Electrical 0.2% proof Young's bending conductivity stress modulus deflection No. (% IACS) (MPa) (GPa) (GPa) Ex 1 44 710 104 94 Ex 2 42 820 103 93 Ex 3 41 840 102 92 Ex 4 42 830 107 97 Ex 5 39 840 105 94 Ex 6 43 820 102 92 Ex 7 40 830 109 100 Ex 8 40 830 108 98 Ex 9 38 870 107 97 Ex 10 36 880 106 96 Ex 11 37 920 104 95 Ex 12 35 940 110 101 Ex 13 33 905 103 93 Ex 14 34 930 106 96 Ex 15 31 1,000 110 100 Ex 16 50 840 107 97 Ex 17 51 830 105 96 Ex 18 50 810 108 97 Ex 19 47 820 108 98 Ex 20 42 840 108 97 Ex 21 41 820 108 98 Ex 22 62 830 107 97 Ex 23 60 620 104 94 Ex 24 55 720 108 97 Ex 25 55 800 109 98 Ex 26 45 810 109 99 Ex 27 55 830 106 95 Ex 28 42 850 109 98 Ex 29 55 830 106 96 Unit of content: mass % “Ex” means Example according to this invention.

TABLE 2 Area ratio Area ratio (%) of (100) (%) of (111) Other plane toward plane toward Ni Co Si Cr elements RD RD C Ex 1 0.4 0.10 50 9 C Ex 2 0.2 0.2 0.10 0.1 Mg: 0.1, 52 10 Sn: 0.1, Zn: 0.5 C Ex 3 5.3 1.26 Production was stopped, due to cracks occurred in hot-working. C Ex 4 2.2 3.5 1.36 Production was stopped, due to cracks occurred in hot-working. C Ex 5 0.3 0.07 0.2 Mg: 0.1 54 13 C Ex 6 5.3 1.26 Production was stopped, due to cracks occurred in hot-working. C Ex 7 5.8 1.38 Production was stopped, due to cracks occurred in hot-working. C Ex 8 2.3 1.68 50 11 C Ex 2-2 2.3 0.55 1 18 C Ex 2-3 2.3 0.55 29 8 Factor of Electrical 0.2% proof Young's bending conductivity stress modulus deflection (% IACS) (MPa) (GPa) (GPa) C Ex 1 68 470 109 99 C Ex 2 66 490 108 98 C Ex 3 Production was stopped, due to cracks occurred in hot-working. C Ex 4 Production was stopped, due to cracks occurred in hot-working. C Ex 5 70 480 107 97 C Ex 6 Production was stopped, due to cracks occurred in hot-working. C Ex 7 Production was stopped, due to cracks occurred in hot-working. C Ex 8 18 740 110 100 C Ex 2-2 40 740 132 121 C Ex 2-3 40 740 124 115 Unit of content: mass % “C Ex” means Comparative Example.

Table 1 shows the examples according to the present invention. Examples 1 to 29 each had the crystal textures fallen within the preferred range according to the present invention, and each were excellent in the 0.2% proof stress, electrical conductivity, Young's modulus, and factor of bending deflection.

Table 2 shows Comparative examples against the present invention. Comparative Examples 1, 2, and 5 were too small in the contents of Ni and/or Co and the content of Si, as compared with the ranges as defined by the present invention, and was poor in the 0.2% proof stress. Comparative Examples 3, 4, 6, and 7 were too large in the contents of Ni and/or Co, and cracks occurred in the hot-rolling, to stop the production. Comparative Example 8 was too high in the content of Si, and was poor in the electrical conductivity.

The following comparative examples are test examples of using the same ingot as that in Example 2.

-   -   Comparative Example 2-2 is a test example produced in the same         manner as in Example 2, except that water-quenching was carried         out immediately after the hot-rolling, and no steps of the         intermediate annealing and cold-rolling 2 were conducted.         However, the area ratio of the (1 0 0) plane oriented toward the         RD was conspicuously low, the area ratio of the (1 1 1) plane         was conspicuously high, and the Young's modulus and the factor         of bending deflection were conspicuously higher than those of         the examples according to the present invention.     -   Comparative Example 2-3 is a test example produced in the same         manner as in Example 2, except that water-quenching was carried         out immediately after the hot-rolling. However, the area ratio         of the (1 0 0) plane oriented toward the RD was conspicuously         low, and the Young's modulus was conspicuously higher than that         of the examples according to the present invention.

TABLE B Step (1) Homogeni- Slow-cooling Solution Step (2) zation Hot- after hot- Face- Cold- Intermediate Cold- heat Cold- Low-temp treatment rolling rolling milling rolling 1 annealing rolling 2 treatment Aging rolling annealing Ex ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ≦50% ∘ C Ex 2-2 ∘ ∘ — * ∘ ∘ — — ∘ ∘ ≦50% ∘ C Ex 2-3 ∘ ∘ — * ∘ ∘ ∘ ∘ ∘ ∘ ≦50% ∘ * Water-quenching was conducted immediately after the hot-rolling. “Ex” means Example according to this invention, and “C Ex” means Comparative Example.

Other examples according to the present invention are shown in Table 3.

TABLE 3 Area ratio Area ratio (%) of (100) (%) of (111) Other plane toward plane toward Ni Co Si Cr elements RD RD Ex 10-2 3.8 0.90 0.1 Mg: 0.1, 47 11 Sn: 0.1, Zn: 0.5 Ex 10-3 3.8 0.90 0.1 Mg: 0.1, 82 4 Sn: 0.1, Zn: 0.5 Ex 18-2 1.3 0.8 0.50 46 9 Ex 18-3 1.3 0.8 0.50 69 7 Ex 25-2 2.3 0.55 43 10 Ex 25-3 2.3 0.55 78 3 Electrical 0.2% proof Young's Factor of bending conductivity stress modulus deflection (% IACS) (MPa) (GPa) (GPa) Ex 10-2 38 880 109 99 Ex 10-3 38 890 78 70 Ex 18-2 50 835 108 99 Ex 18-3 50 840 94 83 Ex 25-2 42 860 108 98 Ex 25-3 42 860 84 75 Unit of content: mass % “Ex” means Example according to this invention.

Examples 10-2, 18-2, and 25-2 of Table 3 are test examples that were produced in the same manner as in the respective examples of Table 1, except that the same ingots as those in Examples 10, 18, and 25 of Table 1 were respectively used, the materials were water-quenched immediately after the hot-rolling, and the intermediate annealing and the cold-rolling 2 were carried out repeatedly two times, and had their characteristics evaluated in the same manner as above. These examples had the area ratios of the (1 0 0) plane oriented toward the RD within the preferred range according to the present invention, and were excellent in the mechanical strength, electrical conductivity, Young's modulus, and factor of bending deflection.

Examples 10-3, 18-3, and 25-3 are test examples that were produced in the same manner as in the respective examples of Table 1, except that the same ingots as those in Examples 10, 18, and 25 of Table 1 were respectively used, and the intermediate annealing and the cold-rolling 2 were carried out repeatedly two times, and had their characteristics evaluated in the same manner as above. These examples had the particularly high area ratios of the (1 0 0) plane oriented toward the RD, and had the particularly low Young's moduli such as 100 GPa or less, and the particularly low factor of bending deflections such as 90 GPa, and were excellent in the 0.2% proof stress and electrical conductivity.

Next, in order to clarify the difference between copper alloy sheet materials produced under the conventional production conditions and the copper alloy sheet material according to the present invention, copper alloy sheet materials were produced under the conventional conditions, and evaluations of the same characteristic items as described above were conducted. The working ratio was adjusted so that, unless otherwise specified, the thickness of the respective sheet material would be the same as the thickness in the examples described above.

Comparative Example 101 Conditions Described in JP-A-2009-007666

An alloy formed by blending the same metal elements as those in Example 1-1, with the balance of Cu and inevitable impurities, was melted in a high-frequency melting furnace, followed by casting at a cooling speed of 0.1 to 100° C./sec, to obtain an ingot. The resultant ingot was maintained at 900 to 1,020° C. for 3 minutes to 10 hours, followed by subjecting to hot working, quenching in water, and then surface milling to remove oxide scale. For the subsequent steps, use was made of the treatments/workings of the following steps A-3 and B-3, to produce a copper alloy c01.

The production steps included one, two times or more solution heat treatments. Herein, the steps were divided into those before and after the final solution heat treatment, so that the steps up to the intermediate solution treatment are designated as Step A-3, while the steps after the intermediate solution treatment are designated as Step B-3.

Step A-3: Cold working at a cross-sectional area reduction ratio of 20% or greater, a heat treatment at 350 to 750° C. for 5 minutes to 10 hours, cold working at a cross-sectional area reduction ratio of 5 to 50%, and a solution heat treatment at 800 to 1,000° C. for 5 seconds to 30 minutes.

Step B-3: Cold working at a cross-sectional area reduction ratio of 50% or less, a heat treatment at 400 to 700° C. for 5 minutes to 10 hours, cold working at a cross-sectional area reduction ratio of 30% or less, and temper annealing at 200 to 550° C. for 5 seconds to 10 hours.

The test specimen c01 thus obtained was different from those in the examples according to this invention, in terms of the slow-cooling down to 350° C. after the hot-rolling, whether conducted or not conducted, in connection with the production conditions, and resulted in a conspicuously high area ratio of the (1 1 1) plane oriented toward the RD, and not satisfying the requirements on the Young's modulus and the factor of bending deflection.

Comparative Example 102 Conditions Described in JP-A-2006-283059

A copper alloy having the same composition as in Example 1-1 according to this invention was melted in the air under charcoal coating with an electric furnace, to judge whether the copper alloy was able to be cast or not. The resultant ingot produced by melting was hot rolled, to finish to thickness 15 mm. Then, this hot-rolled sheet was subjected to cold-rollings and heat treatments (cold-rolling 1→solution continuous annealing→cold-rolling 2→aging→cold-rolling 3→short-time annealing), to produce a copper alloy sheet (c02) with a predetermined thickness.

The test specimen c02 thus obtained was different from that in Example 1 according to this invention, in terms of the slow-cooling down to 350° C. after the hot-rolling, whether conducted or not conducted, and the intermediate annealing and cold-rolling before the solution treatment, whether conducted or not conducted, in connection with the production conditions, and resulted in a conspicuously high area ratio of the (1 1 1) plane oriented toward the RD, and not satisfying the requirements on the Young's modulus and the factor of bending deflection.

Comparative Example 103 Conditions Described in JP-A-2006-152392

An alloy having the same composition as in Example 1-1 according to this invention was melted in the air under charcoal coating in a kryptol furnace, followed by casting in a book mold made of cast iron, to produce an ingot with a size of thickness 50 mm, width 75 mm, and length 180 mm. Then, the surface of the ingot was surface milled, followed by hot rolling at a temperature of 950° C. until that the thickness became 15 mm, and then quenching in water from a temperature of 750° C. or higher. Then, oxide scale was removed, followed by cold-rolling, to give a sheet with a predetermined thickness.

Then, the resultant sheet was subjected to a solution treatment by heating at the temperature for 20 seconds, in a salt bath furnace, followed by quenching in water, and then finish cold-rolling of the second half, to produce a cold-rolled sheet with any of various thicknesses. At that time, as shown below, cold-rolled sheets (c03) were obtained by changing the working ratio (%) in these cold-rollings. These cold-rolled sheets were subjected to aging by changing the temperature (° C.) and the time period (hr) as shown below.

Cold-working ratio: 95%

Solution treatment temperature: 900° C.

Artificial age-hardening temperature×time period: 450° C.×4 hours

Sheet thickness: 0.6 mm

The test specimen c03 thus obtained was different from that in Example 1 according to this invention, in terms of the slow-cooling down to 350° C. after the hot-rolling, whether conducted or not conducted, and the intermediate annealing and cold-rolling before the solution treatment, whether conducted or not conducted, in connection with the production conditions, and resulted in a conspicuously high area ratio of the (1 1 1) plane oriented toward the RD, and not satisfying the requirements on the Young's modulus and the factor of bending deflection.

Comparative Example 104 Conditions Described in JP-A-2008-223136

The copper alloy shown in Example 1 was melted, followed by casting with a vertical continuous casting machine. From the thus-obtained ingot (thickness 180 mm), a sample with thickness 50 mm was cut out, and this sample was heated to 950° C., followed by extracting, and then starting hot-rolling. At that time, the pass schedule was set to the rolling ratio in the temperature range of 950 to 700° C. to be 60% or higher, and to conduct rolling even in the temperature range of lower than 700° C. The final pass temperature of hot-rolling was between 600° C. and 400° C. The total hot-rolling ratio from the ingot was about 90%. After the hot-rolling, the oxide layer at the surface layer was removed by mechanical polishing (surface milling).

Then, after conducting cold-rolling, the sample was subjected to a solution treatment. The temperature change at the time of the solution treatment was monitored with a thermocouple attached to the sample surface, and the time period for temperature rise from 100° C. to 700° C. in the course of temperature rising was determined. The end-point temperature was adjusted in the range of 700 to 850° C., depending on the alloy composition, so that the average grain size (a twin boundary was not regarded as the grain boundary) after the solution treatment would be 10 to 60 μm, and the retention time period in the temperature range of 700 to 850° C. was adjusted in the range of 10 sec to 10 min. Then, the sheet material obtained after the solution treatment was subjected to intermediate cold-rolling at the rolling ratio, followed by aging. The aging temperature was set to a material temperature of 450° C., and the aging time period was adjusted to the time period at which the hardness reached the maximum upon the aging at 450° C., depending on the alloy composition. The optimum solution treatment conditions and the optimum aging time period had been found by preliminary experiments in accordance with the alloy composition. Then, finish cold-rolling was conducted at the rolling ratio. Samples that had been subjected to the finish cold-rolling were then further subjected to low-temperature annealing of placing the sample in a furnace at 400° C. for 5 minutes. Thus, test specimens c04 were obtained. Surface milling was conducted in the mid course, as necessary, and thus the sheet thickness of the test specimens was set to 0.2 mm. The principal production conditions are as described below.

[Conditions of Example 1 of JP-A-2008-223136]

Hot-rolling ratio at below 700° C. to 400° C.: 56% (one pass)

Cold-rolling ratio before solution treatment: 92%

Cold-rolling ratio for intermediate cold-rolling: 20%

Cold-rolling ratio for finish cold-rolling: 30%

Time period for temperature rise from 100° C. to 700° C.: 10 seconds

The test specimens c04 thus obtained were different from that in Example 1 according to this invention, in terms of the slow-cooling down to 350° C. after the hot-rolling, whether conducted or not conducted, and the intermediate annealing and cold-rolling before the solution treatment, whether conducted or not conducted, in connection with the production conditions, and resulted in a conspicuously high area ratio of the (1 1 1) plane oriented toward the RD, and not satisfying the requirements on the Young's modulus and the factor of bending deflection. 

1-9. (canceled)
 10. A copper alloy sheet material for electrical or electronic parts, having an alloy composition containing any one or both of Ni and Co in an amount of 0.5 to 5.0 mass % in total, Si in an amount of 0.2 to 1.5 mass %, optionally Cr in an amount of 0.05 to 0.5 mass %, and optionally at least one selected from the group consisting of Zn, Sn, Mg, Ag, Mn, and Zr in an amount of 0.01 to 1.0 mass % in total, with the balance being Cu and inevitable impurities, wherein the copper alloy sheet material has a 0.2% proof stress in the rolling direction of 500 MPa or more, an electrical conductivity of 30% IACS or more, a Young's modulus of 110 GPa or less, and a factor of bending deflection of 105 GPa or less.
 11. The copper alloy sheet material for electrical or electronic parts according to claim 10, wherein the copper alloy sheet material has an area ratio of (1 0 0) plane oriented toward the rolling direction, which is obtained by analyzing the copper alloy sheet material with EBSD, is 30% or more.
 12. The copper alloy sheet material for electrical or electronic parts according to claim 10, wherein the copper alloy sheet material has an area ratio of (1 1 1) plane oriented toward the rolling direction, which is obtained by analyzing the copper alloy sheet material with EBSD, is 15% or less.
 13. The copper alloy sheet material for electrical or electronic parts according to claim 11, wherein the copper alloy sheet material has an area ratio of (1 1 1) plane oriented toward the rolling direction, which is obtained by analyzing the copper alloy sheet material with EBSD, is 15% or less.
 14. A connector, which is composed of the copper alloy sheet material for electrical or electronic parts according to claim
 10. 15. A method of producing the copper alloy sheet material for electrical or electronic parts according to claim 10, containing, in this order, the steps of: subjecting a copper alloy to give the alloy composition to casting; hot-rolling; cold-rolling 1 at a rolling ratio of 70% or higher; intermediate annealing at 300 to 800° C. for 5 seconds to 2 hours; cold-rolling 2 at a rolling ratio of 3 to 60%; solution heat treatment at 600 to 1,000° C. for 5 seconds to 300 seconds; aging heat treatment at 400 to 600° C. for 0.5 hours to 8 hours; finish cold-rolling at a working ratio of 50% or less; and low-temperature annealing at 300 to 700° C. for 10 seconds to 2 hours, wherein the method of producing further contains, conducting at least any one or both of the following steps [1] and [2]: [1] slowly cooling at a cooling speed of 5 K/second or less to a temperature of 350° C., after the hot-rolling; and [2] carrying out the intermediate annealing and the cold-rolling 2, repeatedly two times or more. 